<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
   <script>
    function tool(func) {
     return function (...args) {
      return func.apply(this, args);
     }
    }
    
    const myConcat = tool(Array.prototype.concat);
    console.log(myConcat([1, 2], [3, 4]),999); // 输出：[1, 2, 3, 4],888
    </script>
</body>
</html>